efda7f3f9c
Takes the first two commits from #15375 and adds suggestions from this comment: https://github.com/bevyengine/bevy/pull/15375#issuecomment-2366968300 See #15375 for more reasoning/motivation. ## Rebasing (rerunning) ```rust git switch simpler-lint-fixes git reset --hard main cargo fmt --all -- --unstable-features --config normalize_comments=true,imports_granularity=Crate cargo fmt --all git add --update git commit --message "rustfmt" cargo clippy --workspace --all-targets --all-features --fix cargo fmt --all -- --unstable-features --config normalize_comments=true,imports_granularity=Crate cargo fmt --all git add --update git commit --message "clippy" git cherry-pick e6c0b94f6795222310fb812fa5c4512661fc7887 ```
90 lines
2.9 KiB
Rust
90 lines
2.9 KiB
Rust
//! Demonstrates how to register and access custom attributes on reflected types.
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use bevy::reflect::{Reflect, TypeInfo, Typed};
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use std::{any::TypeId, ops::RangeInclusive};
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fn main() {
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// Bevy supports statically registering custom attribute data on reflected types,
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// which can then be accessed at runtime via the type's `TypeInfo`.
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// Attributes are registered using the `#[reflect(@...)]` syntax,
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// where the `...` is any expression that resolves to a value which implements `Reflect`.
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// Note that these attributes are stored based on their type:
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// if two attributes have the same type, the second one will overwrite the first.
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// Here is an example of registering custom attributes on a type:
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#[derive(Reflect)]
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struct Slider {
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#[reflect(@RangeInclusive::<f32>::new(0.0, 1.0))]
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// Alternatively, we could have used the `0.0..=1.0` syntax,
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// but remember to ensure the type is the one you want!
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#[reflect(@0.0..=1.0_f32)]
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value: f32,
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}
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// Now, we can access the custom attributes at runtime:
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let TypeInfo::Struct(type_info) = Slider::type_info() else {
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panic!("expected struct");
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};
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let field = type_info.field("value").unwrap();
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let range = field.get_attribute::<RangeInclusive<f32>>().unwrap();
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assert_eq!(*range, 0.0..=1.0);
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// And remember that our attributes can be any type that implements `Reflect`:
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#[derive(Reflect)]
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struct Required;
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#[derive(Reflect, PartialEq, Debug)]
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struct Tooltip(String);
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impl Tooltip {
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fn new(text: &str) -> Self {
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Self(text.to_string())
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}
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}
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#[derive(Reflect)]
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#[reflect(@Required, @Tooltip::new("An ID is required!"))]
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struct Id(u8);
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let TypeInfo::TupleStruct(type_info) = Id::type_info() else {
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panic!("expected struct");
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};
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// We can check if an attribute simply exists on our type:
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assert!(type_info.has_attribute::<Required>());
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// We can also get attribute data dynamically:
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let some_type_id = TypeId::of::<Tooltip>();
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let tooltip: &dyn Reflect = type_info.get_attribute_by_id(some_type_id).unwrap();
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assert_eq!(
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tooltip.downcast_ref::<Tooltip>(),
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Some(&Tooltip::new("An ID is required!"))
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);
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// And again, attributes of the same type will overwrite each other:
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#[derive(Reflect)]
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enum Status {
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// This will result in `false` being stored:
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#[reflect(@true)]
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#[reflect(@false)]
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Disabled,
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// This will result in `true` being stored:
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#[reflect(@false)]
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#[reflect(@true)]
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Enabled,
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}
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let TypeInfo::Enum(type_info) = Status::type_info() else {
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panic!("expected enum");
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};
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let disabled = type_info.variant("Disabled").unwrap();
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assert!(!disabled.get_attribute::<bool>().unwrap());
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let enabled = type_info.variant("Enabled").unwrap();
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assert!(enabled.get_attribute::<bool>().unwrap());
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}
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